Electron-discharge device and method of making the same



M. J. KELLY. ELECTRON DISCHARGE DEVICE AND METHOD OF MAKING THE SAME.

APPLICATION FILED NOV. I5 I919.

Patented; Oct 24!, 1922.

ml/ehfor Merv/ha New 4W W A?) Patented @ct. 2e, was.

- "iterate UNHTE sreresrersnr forties.

MERVIN a. KELLY, OF NEW YORK, n. Y.,"ASSIG1\TOR T WESTERN ELECTRICCOMPANY, INCORPORATED, ormpw YORK, 1\T.'Y., A CORPORATION or NEW YORK.

ELECTRON-DISCHARGE DEVICE AN D METHOl OF MAKING THE SAME.

' Application filed Noveniber 15, 1919. Serial No. 338,213.

To all whom it may concern. 1

Be it known that I, MERVIN KELLY,

a citizen of the United States, residing at New York, in the county ofBronx, State 5 of New York, have invented certain new and usefulImprovements in Electron-Discharge Devices and Methods of Making theSame, of which the following is a full, clear, concise, and exactdescription.

This invention relates to electron discharge devices and toa method ofmanufacturing them.

One object of the invention is'to increase the amount ofpower which maybe applied '15 to an electron discharge device while still keepingwithin the safe limits of'temperature under which the electrodes canfunc- 'tion. I

Another object is the elimination of the objectionable efi'ect which issometimes produced in electron discharge devices, namely blocking, whichis caused partly, at least, by undesirable secondary em1ssion from thethe rovision of a black coatin on the electrodes of electron dischargeevices, particularly the plate and grid. In a preferred form of myinvention using electrodes comis produced on the surface by oxidation ata suitable temperature, preferably about.

900 C. in an electric furnace in the presence of air. jjUSlllg othermetals for elec trodes, such as molybdenum, other suitable blackcoatings may be formed within the spirit of my invention. I Electrondischarge devices'have'been- 'de ficient in their operation in onerespect because only alimited amount'ofi wer could be handled by themwithout eating, the

electrodes beyond a safe temperature. By;

increasing the capacity of the electrodes to radiate heat faster, we canincrease the power applied an'dsti-ll keep the temperature within safelimits. p

Furthermore, electron discharge devices, particularly when considerableamounts of power are handled, have been subject to a @5 blockingphenomenon which has paralyzed Still another object is to eliminate theposed of nickel, a coating of oxide of nickel "21 and 22.

' the tube operation. When strong electron currents are passing, thebombardment of the grid sometimes roduces a secondary emission from theygrid, the flow of which secondary current is opposed in direction to thenormal operating electron or space current. In some cases, thissecondary current has completely neutralized the normal current, andthus blocked the proper functioning of the device.

- A second feature of my invention involves the coating of the grid orcontrol electrode with a substance which acts to substantiall eliminateelectron emission therefrom.- t has been found that nickel oxide, ormolybdenum oxide on the grid surface produce this result. Othersubstances which are semi-insulating in their properties may be used. Itis not here necessary to develop the theory as to why such a coating onthe grid reduces the electron emission therefrom and is suflicient tostate that these coatings do so reduce it.

My invention is illustrated in the drawing which shows a form of deviceto which my invention is. applied.

As illustrated, the device. involving my. invention comprises apreferably evacuated bulb 10 to which the usual base portion 11i's'attached. This base portion provides a support for suitableterminals 12. With in the bulb 10 is a stem portion 13 from which anarbor or post 14-.arises. This arbor 14 provides means for supporting ananode 15, a grid 16 and a filament 17. The anode as shown is in the formof a hollow cylin= der having an oval cross section and is supported bysuitable wires extending from post 14, these wires not being shown. Theanode 15 surrounds the grid 16 and the filamentli. The grid 16 issupported from the arbor 14 by means of wires, such as 18, and thefilament 17. is supported from the arbor 14 by means of wires 19connected to the top of the filament. The filament is supported at itsbottom by means of w1res 20, The wires 20 and 22 also serve as lead-inwires for the current apphed to the filament. Wires '23 and 24 arelead-in wires connecting respectively to the plateand the grid. While Ihave described the mechanical arrangement-of the electrodes tube towhich my invention is applicable.

for the purpose of illustrating one form of In the manufacture andpreparation of the electrodes for assembly within the tube, the plate 15and the grid 16, which arev 1n the form shown, of nickel, are preferablysubjected for a suitable'time in an'electric furnace to a temperatureof-about 900 0., in the presence of air or oxygen. This treatmerit.produces on the surfaces of these elec trodes a coating of black nickeloxide. This 1. coating, possessing as it does the characteristics of ablack body radiator, provides a means whereby the electrodes moreefficiently'radiate heat so that greater amounts of power can besupplied to them .at a. given temperature of operation; p

In the case of the coating applied to the control or grid electrode 16,it is foundthat secondary emission from the grid is' practicallyeliminated and that thermionic emission from the grid, due to thepresence thereon of particles of coating from the fila ment, is likewisesubstantially reduced. H

In some cases, particularly where the 'device is to be used for adetector of minute currents or as adetector oramplifier which operatesintermittently, it is found that the device will operate moreefficiently if, the coating is removed from the surface of the platewhich .lies in the path of the electron stream. The coating may beremoved in any su1table manner and a preferred method of .so removingthe coating comprises the sub jection of this face to the action of ajet of hydrogen or other reducingagent While the face is heated. Anothermethod of. re-

movin the coating is to subject the elec trode; ace to the action of a'blast of abrasive material which efficiently removes the 1. The methodof manufacturing electron discharge devices which comprises producing Ia black. coating on the surfaces of an elecfrom one of said surfaces.

2. The method of manufacturing electron discharge devices whichcomprises produc- 111g a black" coating on the surfaces of an electrodeand then removing the coating trode and then removing the-black coating,from one of said surfaces by means of a reducin agent.

3. he method of manufacturing electron discharge devices which comprisesproducing a black oxide coating on the surfaces of an electrode andthanv removing the coating ing a coating on the surfaces of an electrodespaced apart from one of said surfaces by means of reducing agent.

' 4h The method of manufacturing electron discharge devices whichcomprises producby means of subjecting itto high temperature in thepresence of air and then removing the coating from one of said surfacesby means of a reducing agent.

5. The method of manufacturing electron discharge devices which'comprises producing a coating on the surfaces of an electrode by meansof subjecting it to high temperature in the presence of ai and then"removing the coating from one of said surfaces by means of a blast ofabrasive material.

6. An electron discharge deyice comprising a cathode, an anode and agrid electrode,

said grid electrode being interposed between said cathode and anode, anda coating for said grid electrode capable of substantially eliminatingelectron emission therefrom.

7. An electron discharge device compris-v ing a cathode, an anode, andagrid electrode, said grid electrode being interposed between saidcathode and anode, and a semi-insulating coating for said grid electrodecapable of substantially eliminating electron emission therefrom. I

8. An electron discharge device comprising a cathode and anode, saidanode having one side lying outside the path of electron current, and ablack coating for that side of said electrode.

9. An electron discharge device comprising a cathode and an anode, and ablack coating on said anode.

10. An electron discharge device comprising a cathode and a controlelectrode spaced .apart from said cathode, and a black coating on 'saidcontrol electrode.

11'. An electron discharge device comprisin a cathode, anode and controlelectrode, said control electrode and said cathode bein spaced apart anda black coating on sald anode and control electrode. I

-12. 'An 'electrondischar e device comprising a cathode and an aim c,said' anode having a,surface' faced away from said cathode and a blackcoating for that surface of said anode;

' 13. An electron discharge device comprising a cathode, anode andcontrol electrode, sa d control electrode and said cathode being spaced.apart, a black coatingfor said control electrode anda black coating forall parts of the anode which do not lie in the path of'the electroncurrent.

14. An electron dischar e device comprising a cathode a control e fromsaid cathode, and a coat-. ing of nickel oxide on said controlelectrode.

15, iAn'electron discharge device comprising a cathode, an anode ofnickel and a coatin; r nickel oxide on said an de ectrode of m'ckelv 16.An electron discharge device comprising a cathode, an anode of nickeland a control electrode of nickel, and a coating of nickel oxide forsaid anode and said control electrode.

17. An electron discharge device comprising a cathode, a grid electrodesurrounding said cathode and spaced apart from the same, and a blackcoating for said grid electrode.

18. An electron discharge device comprising a cathode, a grid electrodesurrounding said cathode, an anode surrounding said cathode and saidgrid electrode, and a black coating on said anode and grid electrode.

19. An electron discharge device comprising a cathode, a controlelectrode surrounding said cathode, an anode surrounding said controlelectrode and said cathode, a black coating for said control electrodeand for the side. of the anode facing away from the cathode.

20. An electron discharge device comprising a cathode, a controlelectrode surrounding said cathode, an anode of nickel surrounding saidcontrol electrode and said cathode, and a coating of nickel oxide forsaid control electrode and said anode.

21. An electron discharge device. comprising a cathode, a controlelectrode of nickel surrounding said cathode, an anode of nickelsurrounding said control electrode and said cathode, and a coating ofnickel oxide for said control electrode and for that part of the anodewhich faces away from the cathode.

22. An amplifier comprising a cathode and anode, and a coating havinggood heat radiating qualities on said anode.

23. An electron discharge device comprising cathode, anode and controlelectrodes, said control electrode and said cathode being spaced apart,and a secondary electron suppressing coating on said control electrode.

24. An electron discharge device comprising a. cathode, an anode and a'control electrode, said control electrode and said cathode being spacedapart, a secondary electron suppressing coating on said controlelectrode, and a heat radiating coating on said anode.

In witness whereof, I hereunto subscribe my name this 11th day ofNovember, A. D.

MERVIN J. KELLY.

